The present invention relates to sensor devices, and particularly to a small sensor device capable of presenting a digital display as well as a graph display.
A sensor device such as photoelectric sensor, proximity sensor and the like detects an outward physical state and compares a feature amount representing the physical state with a set threshold. Based on the result of this comparison, the sensor device outputs an ON signal or OFF signal. Generally, the sensor device has thus an output indicator lamp for displaying the output status (on or off) and turns on or off the indicator lamp according to the output status.
A sensor device providing an ON or OFF indication of an output status and further capable of providing recognition of the level of a feature amount has a bar graph indicator formed of a plurality of display segments to indicate the level of the feature amount by the bar graph indicator. For example, a display unit 1 of a sensor device shown in FIG. 1 uses a plurality of display segments 2 to present a bar graph display of a feature amount and display an output status by an output indicator lamp 3. A display unit 4 of a sensor device shown in FIG. 2 presents a digital display of a feature amount level by a numerical indicator 5 and displays an output status by an output indicator lamp 6.
The bar graph display system provides intuitive perception of the display contents and thus can be easily recognized while the system has a limited number of indication stages so that the display resolution is poor and the display range is small. On the other hand, the digital display system has a high display resolution and a large display range while intuitive recognition of numerical contents thereof is disadvantageously difficult.
As discussed above, a sensor device according to the bar graph display system and a sensor device according to the digital display system both have advantages and disadvantages that are contrary to each other. A required effect varies depending on an employed application so that one of the two types of sensors should be selected for use in order to achieve the optimum effect.
A display device constructed to achieve both of the digital display and bar graph display using one display unit is disclosed in Japanese Patent Laying-Open No. 59-160168, for example. According to this document, the display device is configured to present both of the digital and analog displays with one display unit. However, the display device disclosed in the document is of large type and thus it has not been known how to apply such a display device to a small sensor device.
The present invention is made to overcome the technical issues described above and one object of the invention is to provide a small sensor device with superior visible recognizability capable of presenting a graph display as well as a digital display according to selection by a user of the sensor device.
A sensor device according to the present invention includes a first face, a display unit mounted on the first face, and a selector for selecting a display of the display unit. The display unit can selectively display a plurality of numerals and a graph. When a numerical display is to be presented, the plurality of numerals are arranged in a first direction and when a graph display is to be presented, the axial direction of the graph is arranged in the first direction. The selector is located on the first face such that the selector does not overlap the display unit. On an arbitrary line on the first face passing through the display unit orthogonally to the first direction, only the display unit is substantially placed.
Typically the first face is substantially rectangular. In this case, the direction of the longer side of the rectangle may be arranged in the first direction. A plurality of numerals are then arranged in the direction of the longer side of the first face when the display unit presents the numerical display. The direction orthogonal to the first direction, or the direction of the shorter side of the first face corresponds to the direction of the height of the numerals. In the direction of the shorter side relative to the display unit, only the display unit itself is substantially placed. Therefore, a large display can be implemented using almost all of the maximum length of the shorter side. The height of numerals to be displayed is preferably at least half of the length of the shorter side.
According to the present invention as described above, when the sensor device is shaped as a small and thin type (the dimension of the shorter sides of the face having the display unit thereon is small), the sensor device can present a large display so that a graph display and a digital display are both possible depending on selection by the user and accordingly a small sensor device with a superior visible recognizability can be provided.
For nearly sheet-like sensor devices of thin type designed for use by closely contacting them to each other, one of the faces of each device corresponding to the end face of the sheet is unavoidably used as a display surface. In such a case, the display unit of the present invention could provide a display as large as possible as the display which presents a selected one of the numerical display and graph display.
The display unit herein can be constituted of a plurality of display segments. The display unit includes not only the normal 7-segment display unit but a dot matrix display unit. Each display segment can be implemented in a plurality of display states. A plurality of display states include those implemented by turning on/off an LED, illuminating an LED in different colors, blocking/transmitting light through a liquid crystal display, and the like.
More preferably, the sensor device consists of a plurality of faces crossing each other, one of the faces having thereon a display unit, the face on which the display unit is placed has a first dimension in a second direction orthogonal to the first direction (direction of arrangement of displayed numerals and axial direction of the graph), and the first dimension being the minimum among those of a plurality of faces constituting the sensor device. The dimension of the face herein refers to the dimension representing the entire shape of the face, for example, the length of the side of the rectangle and the dimension does not include the dimension of structural details of the face.
The dimension of the face on which the display unit of the sensor device is provided, for example the dimension in the direction of the shorter side is the minimum among the dimensions of faces constituting the sensor device. Since the display unit is mounted on the face with the minimum dimension, a plurality of combined sensor devices can entirely be made compact even if the sensor devices are placed on each other with respective display units aligned.
Still preferably, a plurality of numerals and a graph are displayed on the display unit in different display colors respectively.
As the numerical digital display and the graph display can be presented in different display colors, each display can be provided clearly even if the digital display and the graph display share the digital display portion and the graph display portion.
xe2x80x9cDisplay colorxe2x80x9d refers to the main color employed for display. In the case of the LED, the color of emitted light corresponds to the display color and there is presented no display color when the LED is in the turned off state. In the case of the liquid crystal display, a color different from a base color surrounding displayed numerals or graph corresponds to the display color. If the base color is not black and numerals or graph are displayed in black, black is the display color.
In order to present a numerical display and a graph display in different display colors respectively, display segments presenting a display color which can be changed may be provided or display segments of different display colors may be mixed.
Still preferably, the display unit includes a display segment used for presenting a numerical display and a display segment used for presenting a graph display. The display segment employed for presenting the graph display is selected from the display segment employed for presenting the numerical display and has a display color which can be changed. The display color of the display segment is selected so as to present the numerical display and the graph display respectively in different colors.
The numerical display and the graph display share the display segments so that the cost of the sensor device can be reduced and the contents of a display currently presented can be discerned clearly owing to the display colors.
Still preferably, feature amount acquiring means for acquiring a feature amount indicating a physical state of an object to be sensed, threshold setting means for setting a threshold for determining the feature amount, and display mode selecting means are further provided. A mode of displaying the feature amount by numerals and/or a mode of displaying the threshold by numerals and a mode of displaying the feature amount by a graph are provided as a display mode. The display mode selecting means may be a selector placed on the face having thereon the display unit, a switch placed on another face, or means for selecting a display mode according to a signal input from the outside of the sensor device.
Still preferably, the display unit includes a plurality of display segments having a display color which can be changed. When the feature amount is displayed by a graph, a part of the display segments is presented in a display color different from the display color for the graph so as to indicate the position of the threshold by the position of the part of the display segments.
Still preferably, a displayed range of the numerical value of the feature amount or the threshold is different from a range of the value of the feature amount displayed by the graph.
The displayed range of the feature amount can be changed depending on the numerical display and the graph display, so that the characteristics of respective displays can be exhibited effectively.
According to another aspect of the invention, a sensor device includes feature amount acquiring means for acquiring a feature amount indicating a physical state of an object to be sensed, threshold setting means for setting a threshold to determine the feature amount, and a plurality of display segments, and further includes a display unit presenting a numerical display and display mode selecting means for selecting any of a numerical display mode and a graph display mode. At least a part of the display segments used for presenting the numerical display has a display color which can be changed. In the numerical display mode, the feature amount or the threshold is indicated by numerals in one display color. In the graph display mode, the feature amount is displayed by a graph using display segments selected from the display segments for the numerical display. The position of the threshold in the graph is indicated by displaying a part of the display segments selected from the display segments for the numerical display in a display color different from a display color of the graph such that the position of the part of the display segments corresponds to the position of the threshold.
Using the same display segments, a desired one of the numerical display and the graph display can be presented, and the sensed feature amount and the threshold are represented in different colors respectively in the graph display. Accordingly, a compact sensor device capable of clearly displaying sensed data in a desired display mode can be provided.
The graph display indicating the feature amount may be presented in the same display color as that of numerals, or the display color of the threshold in the graph may be the same as the display color of numerals. If the display color of the graph indicating the feature amount is the same as the display color of numerals, the display color of the display segments presenting a display of the threshold in the graph can be changed. If the display color of the threshold in the graph is the same as the display color of numerals, the display color of the display segments representing the feature amount by the graph can be changed.
According to a further aspect of the invention, a display unit includes a plurality of display segments for displaying a plurality of numerals, and a graph display is presented by using display segments selected from the display segments for presenting a numerical display. The display segments used for the graph display have a display color which can be changed. The display color of the display segments can be selected so that the numerical display and the graph display are presented in different colors respectively.
A desired display mode is selectable and which display is now presented can easily be recognized. Accordingly, the display unit of the present invention can be employed not only in the sensor device but in a wide range of applications in which the numerical display and the graph display are interchanged in a small display space and with a superior visible recognizability.